(1) Field or the Invention
The present invention relates to an adhesive composition for a vinyl halide type resin such as a vinyl chloride resin or a vinylidene chloride resin.
(2) Description of the Related Art
A vinyl halide type resin such as a vinyl chloride resin is widely used in various fields as rigid products such as telephone cards, cash cards, IC cards, records, various plates and pipes and as soft articles such as agricultural films, electric wire coverings and furniture leathers.
These vinyl chloride resins are used in the state laminated with or bonded to other resins or paper according to intended uses as mentioned above. Practically, however, bonding methods for laminating or bonding resins of this type involve problems.
The following methods are often adopted as the bonding means.
(1) A method in which an adhesive of a solution type formed by dissolving a vinyl chloride/vinyl acetate copolymer resin, an acrylic acid ester copolymer, a copolycondensed polyester resin or a thermoplastic polyurethane resin in a solvent is used.
(2) A method in which the surface of a vinyl chloride resin as an adherend is dissolved and bonding is effected before complete scattering of the solvent.
(3) A method in which a dope cement (formed by dissolving a vinyl chloride resin in a solvent) is used for bonding.
In any or the foregoing methods, since a solvent is used, problems arise because whitening, embrittlement and cracking of the vinyl chloride resin are readily caused.
As the means for obviating this disadvantage, use of a solvent-free adhesive such as a solvent-free epoxy resin, a solvent-free reactive acrylic resin or a solvent-free polyurethane adhesive has been proposed. However, since large amounts of a plasticizer, a stabilizer, an antistatic agent and the like are contained in a vinyl chloride resin, a satisfactory bonding strength cannot be obtained by any of these adhesives.